1. Field of the Invention
The present invention relates to a reactive silicon dioxide compound and an optical protective film, and in particular relates to an optical protective film containing a reactive silicon dioxide compound, wherein the reactive silicon dioxide compound may reduce phase difference and enhance transparency of the optical protective film.
2. Description of the Related Art
Nano-scaled silicon dioxide material is used in polymer material as a filler material to increase surface hardness, mechanical strength and heat tolerance of the polymer material. Such a polymer material is widely applied in coating material, film, and the surface treatment for automobiles.
At present, nano-scaled silicon dioxide material is applied in optical protective films. However, for optical protective films, the greater the amount of nano-scaled silicon dioxide material used, the greater the haze therein.
A. Tagaya, H. Ohkita, M. Mukaoh, R. Sakaguchi, Y. Koike, Science, 301, 812, (2003) discloses that a polymer material is added into an inorganic salt crystalline compound to reduce an R0 value thereof. However, the Rth value is not reduced.
U.S. Pat. No. 6,828,006 and U.S. Pat. No. 6,844,033 discloses that the maximum content of a nano-scaled silicon dioxide material used to making a triacetate cellulose triacetate cellulose film should be 0.3%, if more than 0.3% is used in a cellulose triacetate cellulose film, transparency and haze of an optical protective film would decrease and increase, respectively.
A novel optical protective film which has low phase difference and low haze is desired. Therefore, in the invention, an optical protective film containing a reactive nano-scaled silicon dioxide material which has low phase difference and low haze is provided. Briefly, due to surface modification of a reactive nano-scaled silicon dioxide material, the reactive nano-scaled silicon dioxide material may be more compatible with a polymer thereby increasing transparency and decreasing haze.
The reactive silicon dioxide compound of the invention may improve the out-of-plane problem of polarized light optical protective film, reduce light leakage at large view angles and color shift, and reduce contrast of bright state and dark state. Furthermore, the reactive silicon dioxide compound of the invention may be applied in plastic solar energy condenser lenses of the optical field.